The SPM4 Catalog contains absolute proper motions, celestial coordinates, and B,V photometry for 103,319,647 stars and galaxies between the south celestial pole and -20 degrees declination. The catalog is roughly complete to V=17.5. It is based on photographic and CCD observations taken with the Yale Southern Observatory's double-astrograph at Cesco Observatory in El Leoncito, Argentina. The first-epoch survey, taken from 1965 to 1979, was entirely photographic. The second-epoch survey is approximately 1/3 photographic (taken from 1988 to 1998) and 2/3 CCD-based (taken from 2004 through 2008). Full details about the creation of the SPM4.0 catalog can be found in the paper, and also in the document "spm4_doc.txt" file which describes the original files, accessible from http://www.astro.yale.edu/astrom/spm4cat/
The SPM Catalog 2.0 provides positions, absolute proper motions and photographic BV photometry for over 320,000 stars and galaxies. The Catalog covers an area of ~3700 square degrees in an irregularly bounded band between declinations of -43 and -22 degrees, with a slight extension near the South Galactic Pole, but excluding fields in the plane of the Milky Way. Stars cover the magnitude range 5<V<18.5. The standard errors for the best measured stars are as follows: 20 mas for positions in each coordinate; 2mas/yr for absolute proper motions and 0.05mag for B and V magnitudes. Standard error estimates of positions, absolute proper motions and magnitudes are given for each individual object. In addition to the Catalog, a list of CCD calibrating sequences is provided. Note that all fields (and objects) contained in the 1.0 version of the Catalog are also included in this version. The values of the astrometric parameters for these objects, however, may be different due to refinements in the reduction procedure, (i.e. the SGP fields were re-reduced for inclusion in the SPM catalog 2.0).
The file table 2 gives the results of various tests and noise measurements performed on time serie of extragalactic radio source coordinates. Systematic and random behaviours in time serie of individual determinations of cooordinates for 283 sources over 1987-1999 are investigated. The random variability of the source coordinates is characterized by the {chi}^2^ test (Bevington, 1969, p.187) and the "goodness of fit (gof)" (Bevington, 1969, p.188). The Allan variance method (Allan, 1966, Proc. IEEE, vol. 54, 221) is used to investigate spectral characteristics of the time series. The source structure index (Fey & Charlot, 1997ApJS..111...95F, 2000, Cat. <J/ApJS/128/17>) qualifies the level of position disturbance expected at the date of the map (1 for the less disturbed, 4 for the most disturbed). The estimation of "linear rates" in the coordinates is a qualifier of the systematic parts of the source instability. This table contains the 283 best observed sources and is divided in three parts, with the left hand side giving general information and counts, the middle part giving statistics in the source local frame, and the right hand side giving statistics in the equatorial frame.
The connection between the optical reference frame and the radio one constitutes one of the main purposes of the astrometry. The paper is pointing out the contribution of the Bucharest Observatory in this direction. The statistic analysis of the standard errors for the astrometric PPM and TYCHO stars is presented.
The catalogue by Johannes Hevelius with the positions and magnitudes of 1564 entries was published by his wife Elisabeth Koopman in 1690. We provide a machine-readable version of the catalogue, and briefly discuss its accuracy on the basis of comparison with data from the modern Hipparcos Catalogue. We compare our results with an earlier analysis by Rybka (1984), finding good overall agreement. The magnitudes given by Hevelius correlate well with modern values. The accuracy of his position measurements is similar to that of Brahe, with error distributions with widths of about 2 arcmin for longitudes and latitudes, but with more errors larger than 5 arcmin than expected for a Gaussian distribution. The position accuracy decreases slowly with magnitude. The fraction of stars with position errors larger than a degree is 1.5 per cent, rather smaller than the fraction of 5 per cent in the star catalogue of Brahe.
Tycho Brahe completed his catalogue with the positions and magnitudes of 1004 fixed stars in 1598. This catalogue circulated in manuscript form. Brahe edited a shorter version with 777 stars, printed in 1602, and Kepler edited the full catalogue of 1004 stars, printed in 1627. We provide machine-readable versions of the three versions of the catalogue, describe the differences between them and briefly discuss their accuracy on the basis of comparison with modern data from the Hipparcos Catalogue. We also compare our results with earlier analyses by Dreyer (1916Obs....39..127D, On Tycho Brahe's manual of trigonometry) and Rawlins (1993BAAS...25.1335R, Atmospheric Clarity and Tycho's Fake Stars), finding good overall agreement. The magnitudes given by Brahe correlate well with modern values, his longitudes and latitudes have error distributions with widths of 2-arcmin, with excess numbers of stars with larger errors (as compared to Gaussian distributions), in particular for the faintest stars. Errors in positions larger than about 10-arcmin, which comprise about 15 per cent of the entries, are likely due to computing or copying errors.
In late antiquity and throughout the middle ages, the positions of stars on the celestial sphere were obtained from the star catalogue of Ptolemaios. A catalogue based on new measurements appeared in 1437, with positions by Ulugh Beg, and magnitudes from the 10th-century astronomer al-Sufi. We provide machine-readable versions of these two star catalogues, based on the editions by Toomer (1998) and Knobel (1917), and determine their accuracies by comparison with the modern Hipparcos Catalogue. The magnitudes in the catalogues correlate well with modern visual magnitudes; the indication `faint' by Ptolemaios is found to correspond to his magnitudes 5 and 6. Gaussian fits to the error distributions in longitude/latitude give widths sigma ~27-arcmin/23-arcmin in the range |{Delta}{lambda},{Delta}{beta}|<50-arcmin for Ptolemaios and {sigma}~22-arcmin/18-arcmin\ in Ulugh Beg. Fits to the range |{Delta}{lambda},{Delta}{beta}<100-arcmin gives 10-15 per cent larger widths, showing that the error distributions are broader than gaussians. The fraction of stars with positions wrong by more than 150-arcmin is about 2 per cent for Ptolemaios and 0.1 percent in Ulugh Beg; the numbers of unidentified stars are 1 in Ptolemaios and 3 in Ulugh Beg. These numbers testify to the excellent quality of both star catalogues (as edited by Toomer and Knobel).
The method proposed in Paper I [Tosi et al., AJ, 102, 951 (1991)] to study the star formation histories in nearby irregulars is here applied to the galaxies DDO 210 and NGC 3109. To this purpose we have obtained deep CCD photometry of two regions in DDO 210 and three regions in NGC 3109, reaching V = 24 with the required accuracy of Sigma(V) <= 0.1 mag. Major information on the stellar populations, star formation rates, and initial mass functions of these regions in the last 1 Gyr are derived from the comparison of the observational color-magnitude diagrams and luminosity functions, with the corresponding synthetic diagrams and luminosity functions generated by a numerical simulation code based on stellar evolutionary tracks. In general, for both galaxies we find that in the last 1 Gyr the star formation activity has been rather continuous, possibly occurring in long episodes of moderate activity separated by short quiescent periods. According to our models the metallicity should be fairly low (in the range 0.05 <= Z/Zsun <= 0.5) and the initial mass function exponent in the vicinity of Salpeter's value, i.e., slightly flatter than in the solar neighborhood. The studied regions of NGC 3109 appear to contain different stellar populations (i.e., with slightly different metallicity and star formation histories), whereas those of DDO 210 seem to have fairly similar stellar contents, although for this galaxy the interpretation is more uncertain. As a by-product of our method we find that the distance modulus to DDO 210 should be (m-M)0 approx. 28, which places this galaxy beyond the edge of the Local Group.
1214 individual measurements of radial velocities made with CORAVEL-type spectrometer (Tokovinin, 1987AZh....64..196T) are presented for 1134 stars in 19 northern Kapteyn's areas. Precise coordinates are given for all these stars. Proper motions of stars are taken from NLTT (Luyten, 1979, Cat. <I/98>), PPM (Roser, Bastian, 1991, Cat. <I/146> and <I/193>), NPM1 (Klemola, Hanson, Jones, 1987, Cat. <I/200>) and Four-million catalog (Kuimov, 1992, In: On the four-million catalog of stars, eds. Izd. MGU, Moscow, P.27.; Glushkova et al., 1996PAZh...22..850G). A list of suspected binary stars and stars with variable radial velocities is also given. Two-dimensional spectral classification for these area is available (Bartaya, 1979AbaOB..51....1B).
Positions for a total of 3487 stars, scattered over 14 regions, have been determined using the Danish 1.5-m telescope at La Silla. The 14 regions are centred on one of the southern galactic clusters NGC 1981, 2287, 2437, 2451, 2516, 2546, 2547, 2548, 3114, 3532, IC 2391, 2395, 2602 and Trumpler 10. Combining the Ritchey-Chretien reflector optics with a single element Schmidt-type corrector, gives a considerably enlarged flat field (radius about 25 minutes of arc, or 95mm) with stellar images of excellent definition. With the exception of distortion, which can be allowed for, the effect of the primary aberrations is negligible. A frame of reference has been established for each region using ESO Schmidt plates centred on the clusters, each plate containing from 20 to 35 measurable Perth 70 stars. These objects have served for determining positions of some 200 to 400 fainter stars within a central field of 25 minutes of arc radius, covering the corresponding 1.5-m plates. The fainter stars serve as a secondary standard. Based on three 1.5-m plates for each region, taken on different nights, an internal mean error in one plate position in the range 0.030 to 0.048 seconds of arc has been derived.
